[pluma]

Sure, yes, if his activity would have involved taking over responsibility for people he could easily take with him if he decided to end his life, then it'd have been perfectly understandable why they would want to prevent that.

But we're talking about a college student. Sure, maybe he shouldn't be allowed in the chemistry lab or given roof access, but what does banning him from college grounds prevent that he can't do outside of it?

Besides, if he was so dangerous to warrant banning him from college grounds just so he couldn't get a chance to harm or kill others (e.g. strap bombs to himself and blow people up), he was probably too dangerous to rely on him to respect the ban. This is the point where you involve the police instead of risking to provoke him further -- and then this isn't just a mental issue, it's a direct threat. But as it seems, this wasn't what happened, even remotely.